IntroPart 1

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Intro-Part 1

• Introduction to Database Management Ch 1 2

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Important Points

• Databases are everywhere
• Data independence and abstraction
• Three Schema Architecture
• DBMS characteristics and Features

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Databases are everywhere

• What is a database?
• What is a database management system (DBMS)?
• Examples?

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Example University Database
How would you do this without a database? What
types of challenges would you face?
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File-Based System
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Data Independence and Abstraction

• The major problem with developing applications
  based on files is that the application is
  dependent on the file structure.
• That is, there is no program-data independence
  separating the application from the data it is
  manipulating.
• If the data file changes, the code that accesses
  the file must be changed in the application.
• One of the major advantages of databases is they
  provide data abstraction.
• Data abstraction allows the internal definition
  of an object to change without affecting programs
  that use the object through an external
  definition.

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Three Schema Architecture
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DBMS

• A database management system provides efficient,
  convenient, and safe shared (i.e., multi-user)
  storage and access to massive amounts of
  persistent data.
• Efficient - Able to handle large data sets and
  complex queries without searching all files and
  data items.
• Convenient - Easy to write queries to retrieve
  data.
• Safe - Protects data from system failures and
  hackers.
• Massive - Database sizes in gigabytes and
  terabytes.
• Persistent - Data exists after program execution
  completes.
• Shared - More than one user can access and update
  data at the same time while preserving
  consistency.
• Interrelated True of relational DBMS.

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Common Features of a DBMS

• Database Definition The database is described to
  the DBMS using a Data Definition Language (DDL).
  The DDL allows the user to create data structures
  in the data model used by the database.
• Nonprocedural Access Once a database has been
  created in a DBMS using a DDL, the user accesses
  the data using a Data Manipulation Language
  (DML). The standard DML is SQL.
• Application Development Graphical tools for
  developing forms and reports using non-procedural
  access
• Procedural language interface A language that
  combines nonprocedural access with procedural
  programming.
• Transaction Processing Perform scheduling of
  operations and implements concurrency control
  algorithms.
• Database Tuning Tools to monitor and improve
  database performance.

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University Database
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University Database (ERD)
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Nonprocedural Access

• Query request for data to answer a question
• Indicate what parts of database to retrieve not
  the procedural details
• Improve productivity and improve accessibility
• SQL SELECT statement and graphical tools

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Graphical Tool for Nonprocedural Access
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SQL Examples

• Retrieve all products in the database
• SELECT sku, name, desc, inventory FROM product
• Retrieve all products where inventory lt 10
• SELECT name, inventory FROM product WHERE
  inventory lt 10
• Insert a new product into the database
• INSERT INTO product VALUES ('12345678','Soap',
  'Ivory Soap',100)